Sexual dimorphism in intestinal absorption and lymphatic transport of dietary lipids

The Impact of Cannabidiol (CBD) on Lipid Absorption and Lymphatic Transport in Rats

Background: Cannabidiol (CBD) exerts diverse metabolic effects, yet its influence on intestinal lipid metabolism remains unclear. Methods: In this study, we investigated whether short-term (one-week) CBD treatment affects lipid absorption and transport through the lymphatic system using a validated lymph fistula model. Results: CBD treatment significantly enhanced the transport of radiolabeled triglycerides through the lymphatic system. This effect appeared specific, as CBD did not substantially alter cholesterol output in the lymph. Chemical assays indicated that CBD treatment did not significantly alter total triglycerides, cholesterol, phospholipids, or non-esterified fatty acid levels in the lymph. However, it significantly enhanced the lymphatic output of apolipoprotein A4 (ApoA4) and apolipoprotein A1 (ApoA1). Additionally, gene expression analysis revealed a downregulation of vascular endothelial growth factor receptor 1 (Flt1) in the small intestine, leading to increased lymphatic lacteal permeability and altered lipid transport dynamics. Conclusions: These findings indicate that short-term CBD treatment modulates lymphatic lipid composition and apolipoprotein secretion by regulating lymphatic lacteal function, thereby influencing lipid transport and metabolism. This study provides novel insights into CBD's role in facilitating TG-rich lipoprotein transport via the lymphatic system, highlighting its potential therapeutic applications in lipid-related disorders.

Development and validation of a predictive model for carotid atherosclerosis in postmenopausal women

With the global aging of the population, menopausal women face higher cardiovascular disease (CVD) risks, with carotid atherosclerosis as the primary pathological basis. However, no effective tools exist for assessing carotid atherosclerosis risk, and this study fills the gap in predictive tools in this field. Using data from 4,446 menopausal women in Shenzhen, we developed and validated a Nomogram model for carotid atherosclerosis risk. The sample was divided into training (2,178), internal validation (934), and external validation (1,334) sets. Variables were selected using logistic regression and LASSO, including age, systolic blood pressure (SBP), lipoprotein a (LPa), non-HDL cholesterol (Non-HDL-C), TC/HDL-C ratio, glycosylated hemoglobin (HbA1c), and blood glucose (GLU). Random Forest validation confirmed the model's robustness. The Nomogram's C-index was 0.706 (training), 0.664 (internal), and 0.668 (external), with Random Forest results of 0.721, 0.662, and 0.661, respectively. Calibration and decision curve analyses demonstrated the model's accuracy and clinical utility. Additionally, a slight negative correlation between age and GLU (OR = 0.689, P = 0.068) suggested reduced glycemic risk with age. This model provides a scientific basis for early risk assessment and personalized interventions for menopausal women, guiding future research on related biological mechanisms.

Transport functions of intestinal lymphatic vessels

Lymphatic vessels are crucial for fluid absorption and the transport of peripheral immune cells to lymph nodes. However, in the small intestine, the lymphatic fluid is rich in diet-derived lipids incorporated into chylomicrons and gut-specific immune cells. Thus, intestinal lymphatic vessels have evolved to handle these unique cargoes and are critical for systemic dietary lipid delivery and metabolism. This Review covers mechanisms of lipid absorption from epithelial cells to the lymphatics as well as unique features of the gut microenvironment that affect these functions. Moreover, we discuss details of the intestinal lymphatics in gut immune cell trafficking and insights into the role of inter-organ communication. Lastly, we highlight the particularities of fat absorption that can be harnessed for efficient lipid-soluble drug distribution for novel therapies, including the ability of chylomicron-associated drugs to bypass first-pass liver metabolism for systemic delivery. In all, this Review will help to promote an understanding of intestinal lymphatic-systemic interactions to guide future research directions.

Protective role of Pannexin1 in lymphatic endothelial cells in the progression of atherosclerosis in female mice

Atherosclerosis is a progressive arterial disease arising from imbalanced lipid metabolism and a maladaptive immune response. The lymphatic system ensures tissue fluid homeostasis, absorption of dietary fats and trafficking of immune cells to draining lymph nodes, thereby potentially affecting atherogenesis. Endothelial cell-specific deletion of Pannexin1 (Panx1) in apolipoprotein E-deficient (Apoe-/-) mice increased atherosclerosis, suggesting a protective role for Panx1 channels in arterial endothelial function. Here, we investigated the role of Panx1 in lymphatic endothelial cells (LECs) in the initiation and the progression of atherosclerosis. Male or female Prox1-CreERT2+Panx1fl/flApoe-/- and Panx1fl/flApoe-/- mice were fed a high cholesterol diet (HCD) for 6 or 10 weeks. Tamoxifen-induced deletion of Panx1 was performed before or after 4 weeks of HCD. Body weight and serum lipid profiles were determined. The atherosclerotic plaque burden was assessed by Sudan-IV staining on thoracic-abdominal aortas and in aortic roots. Plaque composition was determined by immunohistochemistry. No differences in serum cholesterol, LDL and HDL were observed between genotypes and between sexes after HCD. Bodyweight, serum triglycerides and free fatty acid levels were higher before and after 6 weeks of HCD in male Prox1-CreERT2+Panx1fl/flApoe-/- and control Panx1fl/flApoe-/- mice compared to females of the same genotypes, which was associated with more lipids and inflammatory cells in their atherosclerotic plaques. In contrast, the atherosclerotic plaque burden was higher in female mice. The progression of atherosclerosis in male mice was not different between genotypes. However, female Prox1-CreERT2+Panx1fl/flApoe-/- mice showed enhanced progression of atherosclerosis compared to Panx1fl/flApoe-/- controls of the same sex. In addition, atherosclerotic lesions in female, but not in male, Prox1-CreERT2+Panx1fl/flApoe-/- mice showed T cell enrichment. Altogether, our results reveal differential sex-dependent effects of Panx1 in lymphatic endothelium on the progression of atherosclerosis.

Chemical Inhibition of NRF2 Transcriptional Activity Influences Colon Function and Oestrogen Receptor Expression in Mice at Different Ages

We aim to investigate whether chemical inhibition of NRF2 transcriptional activity (TA) influences distal colon contractions, particularly in an age-dependent manner in females, and whether it impacts oestrogen receptor signalling in female mice. This study was performed on 3 and 6-month-old female mice treated with ML385 (30 mg/kg) or a vehicle for 7 days (i.p.). The colon functionality was verified with a colon bead expulsion test; serum samples were collected for oestradiol levels, and colon samples were stored for various histological analyses. The results show that the seven-day treatment of ML385 significantly downregulated TA (p < 0.05) and impacted its contractility. Additionally, young females treated with ML385 exhibited an increase in goblet cell number and significantly increased ERα, but not ERβ, especially in older mice. It is worth noting that the basal level of the membrane oestrogen receptor GPR30 was higher in older mice within the epithelial layer, and ML385 treatment led to a downregulation of GPR30 in 6-month-old mice. In summary, ML385 decreases NRF2 TA in the colon and impacts its contractility and goblet cell numbers. Additionally, NRF2 TA influences the expression of oestrogen receptors in the colons of female mice.

Essential Fatty Acids along the Women’s Life Cycle and Promotion of a Well-balanced Metabolism

Abstract:

Linoleic acid (ω-6 LA) and α-linolenic acid (ω-3 ALA) are essential fatty acids (EFA) for human beings. They must be consumed through diet and then extensively metabolized, a process that plays a fundamental role in health and eventually in disease prevention. Given the numerous changes depending on age and sex, EFA metabolic adaptations require further investigations along the women’s life cycle, from onset to decline of the reproductive age. Thus, this review explains women’s life cycle stages and their involvement in diet intake, digestion and absorption, the role of microbiota, metabolism, bioavailability, and EFA fate and major metabolites. This knowledge is crucial to promoting lipid homeostasis according to female physiology through well-directed health strategies. Concerning this, the promotion of breastfeeding, nutrition, and physical activity is cardinal to counteract ALA deficiency, LA/ALA imbalance, and the release of unhealthy derivatives. These perturbations arise after menopause that compromise both lipogenic and lipolytic pathways. The close interplay of diet, age, female organism, and microbiota also plays a central role in regulating lipid metabolism. Consequently, future studies are encouraged to propose efficient interventions for each stage of women's cycle. In this sense, plant-derived foods and products are promising to be included in women’s nutrition to improve EFA metabolism.

Extra Virgin Olive Oil Reduces the Risk of Non-Alcoholic Fatty Liver Disease in Females but Not in Males: Results from the NUTRIHEP Cohort

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease worldwide. One way to resolve this reversible condition is by making dietary changes. Extra virgin olive oil (EVOO) is often associated with an improvement in this disease. The aim of this study was to explore the protective role of EVOO on NAFLD conditions, stratified by gender.

METHODS

The study cohort included 1426 participants assessed in the second recall of the NUTRIHEP cohort (2014-2018), subdivided by gender and dividing the EVOO intake into quartiles of daily gram intake.

RESULTS

The results indicated a protective role of the last quartile of EVOO only for female subjects, OR = 0.43, p = 0.02, 0.21 to 0.85 at 95% C.I., whereas in the male sub-cohort, the effect was not statistically significant.

CONCLUSIONS

The protective role of EVOO is different between genders. This difference has not been explored in the literature, so we conclude that this is one of the few papers in the literature to evaluate a gender difference in the intestinal absorption of humans based on an epidemiological study.

Intestinal monocarboxylate transporter 1 mediates lactate transport in the gut and regulates metabolic homeostasis of mouse in a sex-dimorphic pattern

The monocarboxylate transporter 1 (MCT1), encoded by gene Slc16a1, is a proton-coupled transporter for lactate and other monocarboxylates. MCT1-mediated lactate transport was recently found to regulate various biological functions. However, how MCT1 and lactate in the intestine modulate the physiology and pathophysiology of the body is unclear. In this study, we generated a mouse model with specific deletion of Slc16a1 in the intestinal epithelium (Slc16a1 IKO mice) and investigated the functions of MCT1 in the gut. When fed a high-fat diet, Slc16a1 IKO male mice had improvement in glucose tolerance and insulin sensitivity, while Slc16a1 IKO female mice only had increased adiposity. Deficiency of intestinal MCT1 in male mice was associated with downregulation of pro-inflammatory pathways, together with decreased circulating levels of inflammatory cytokines including tumor necrosis factor alpha (TNFα) and C-C motif chemokine ligand 2 (CCL2). Lactate had a stimulatory effect on pro-inflammatory macrophages in vitro. The number of intestinal macrophages was reduced in Slc16a1 IKO male mice in vivo. Intestinal deletion of Slc16a1 in male mice reduced interstitial lactate level in the intestine. In addition, treatment of male mice with estrogen lowered interstitial lactate level in the intestine and abolished the difference in glucose homeostasis between Slc16a1 IKO and wild-type mice. Deficiency of intestinal MCT1 also blocked the transport of lactate and short-chain fatty acids from the intestine to the portal vein. The effect of Slc16a1 deletion on glucose homeostasis in male mice was partly mediated by alterations in gut microbiota. In conclusion, our work reveals that intestinal MCT1 regulates glucose homeostasis in a sex-dependent manner.

Mechanisms and functions of intestinal vascular specialization

The intestinal vasculature has been studied for the last 100 years, and its essential role in absorbing and distributing ingested nutrients is well known. Recently, fascinating new insights into the organization, molecular mechanisms, and functions of intestinal vessels have emerged. These include maintenance of intestinal epithelial cell function, coping with microbiota-induced inflammatory pressure, recruiting gut-specific immune cells, and crosstalk with other organs. Intestinal function is also regulated at the systemic and cellular levels, such that the postprandial hyperemic response can direct up to 30% of systemic blood to gut vessels, while micron-sized endothelial cell fenestrations are necessary for nutrient uptake. In this review, we will highlight past discoveries made about intestinal vasculature in the context of new findings of molecular mechanisms underpinning gut function. Such comprehensive understanding of the system will pave the way to breakthroughs in nutrient uptake optimization, drug delivery efficiency, and treatment of human diseases.

The effects of sex hormones on the size of intestinal lipoproteins

Larger intestinal lipoproteins are more likely to be retained longer in the intestinal wall, allowing more time for their fat to be hydrolyzed and subsequently taken up by the abdominal viscera. Since men generally accumulate more abdominal visceral fat than women, we sought to determine if males produce larger intestinal lipoproteins compared to females. Using the conscious lymph fistula mouse model, we discovered that the male mice indeed produced larger intestinal lipoproteins than the female mice when they were intraduodenally infused with lipid emulsion. We then employed our differentiated Caco-2 cell model with semipermeable membrane system to determine the effects of sex hormones on the size of intestinal lipoproteins. Lipoprotein size was quantitatively measured by calculating the ratio of triglycerides (TG)/Apolipoprotein B (ApoB) and by analyzing their transmission electron micrographs. Our studies showed that while there was no dose-dependent effect of estrogen and progesterone, testosterone significantly increased the size of lipoproteins. When these hormones were combined to resemble the physiological concentrations observed in males and the different ovarian cycle phases in premenopausal females, both the male and luteal groups had significantly larger lipoproteins than the ovulatory group; and the male group also had significantly larger lipoproteins than the follicular group. The ovulatory group secreted a significantly lower amount of TG than the male and luteal groups. ApoB was comparable among all these groups. These findings support our hypothesis that, through their testosterone effects, males are more likely to produce larger intestinal lipoproteins. Larger lipoproteins tend to remain longer in the intestinal wall and may facilitate fat uptake preferentially by the abdominal viscera. Our studies may partly explain why men are more prone to accumulating abdominal visceral fat, which is an independent predictor of mortality.

Sexual Dimorphism in Lipid Metabolism and Gut Microbiota in Mice Fed a High-Fat Diet

The gut microbiome plays an essential role in regulating lipid metabolism. However, little is known about how gut microbiome modulates sex differences in lipid metabolism. The present study aims to determine whether gut microbiota modulates sexual dimorphism of lipid metabolism in mice fed a high-fat diet (HFD). Conventional and germ-free male and female mice were fed an HFD for four weeks, and lipid absorption, plasma lipid profiles, and apolipoprotein levels were then evaluated. The gut microbiota was analyzed by 16S rRNA gene sequencing. After 4-week HFD consumption, the females exhibited less body weight gain and body fat composition and significantly lower triglyceride levels in very-low-density lipoprotein (VLDL) and cholesterol levels in high-density lipoprotein (HDL) compared to male mice. The fecal microbiota analysis revealed that the male mice were associated with reduced gut microbial diversity. The female mice had considerably different microbiota composition compared to males, e.g., enriched growth of beneficial microbes (e.g., Akkermansia) and depleted growth of Adlercreutzia and Enterococcus. Correlation analyses suggested that the different compositions of the gut microbiota were associated with sexual dimorphism in body weight, fat mass, and lipid metabolism in mice fed an HFD. Our findings demonstrated significant sex differences in lipid metabolism and the microbiota composition at baseline (during LFD), along with sex-dependent responses to HFD. A comprehensive understanding of sexual dimorphism in lipid metabolism modulated by microbiota will help to develop more sex-specific effective treatment options for dyslipidemia and metabolic disorders in females.

Concise review of lipidomics in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) encompasses simple liver steatosis, nonalcoholic steatohepatitis (NASH), and liver fibrosis that can progress to cirrhosis. NAFLD has become the principal cause of chronic liver disease in many parts of the world. Lipidomic studies, by allowing to determine concentrations of lipid classes and fatty acid composition of different lipid species, have been of great interest to help understand NAFLD pathophysiology and potentially identify novel biomarkers for diagnosis and prognosis. Indeed, lipidomic data give information on qualitative lipid abnormalities associated with NAFLD. The aim of our article was to create a comprehensive and more synthetic review of main results from lipidomic studies in NAFLD. Literature was searched for all human lipidomic studies evaluating plasma samples of individuals with NAFLD. Results were regrouped by the degree of liver damage, either simple steatosis, NASH or liver fibrosis, and presented by lipid categories. Overall, we summarized the main lipidomic abnormalities associated with NAFLD as follows: modification of free fatty acid distribution, increase in ceramides, reduced phosphatidylcholine / phosphatidylethanolamine ratio, and increase in eicosanoids. These lipid abnormalities are likely to promote NASH and liver fibrosis by inducing mitochondrial dysfunction, apoptosis, inflammation, oxidation, and endoplasmic reticulum stress. Although these lipidomic abnormalities are consistently reported in many studies, further research is needed to clarify whether they may be predictive for liver steatosis, NASH or liver fibrosis.

The lack of transcriptionally active Nrf2 triggers colon dysfunction in female mice - The role of estrogens

BACKGROUND AND AIM

The proper functioning of the gastrointestinal system relies on an intricate crosstalk between a plethora of cell types and signaling pathways. Recently we identified that the lack of NRF2 transcriptional activity (NRF2 tKO) triggers significant colon microscopical alterations, still they do not affect the general functioning of mice. Therefore, in this study, we aimed to address the gender-dependent impact of NRF2 transcriptional deficiency on colon function, and relate them to an established model of inflammatory bowel disease (IBD).

METHODS

In the study we subjected 3- and 6-month old mice deficient in IL-10 and NRF2 transcriptional activity and wild-type counterparts to tests assessing colon functionality, and histological analyses. To address the role of estrogens, we attempted to rescue the phenotype by the delivery of 17β-estradiol through subcutaneous implants.

RESULTS

In females, NRF2 transcriptional abrogation, like IL-10 deficiency, triggers a functional and microscopic phenotype, that resembles IBD. The females are significantly more affected by the dysfunctional phenotype, and the functional impairmentdecreases with age. We found that NRF2 transcriptional activity influences 17β-estradiol level and the estrogen receptors expression and location. Exogenous delivery of 17β-estradiol normalized colon motility in the NRF2 tKO mice, which is related to enhanced ERβ signaling.

CONCLUSIONS

Summing up, in this study, we underline that NRF2 transcriptional deficiency or the lack of IL-10 results in pronounced GI functional decline in young females. Mechanistically, we show that the impaired distal colon motility is dependent on ERβ signaling. Targeting estrogen signaling seems a promising therapeutic strategy to counteract colonic dysfunction.